In photolithography process, as one of the producing processes for a micro device such as a semiconductor device or a liquid crystal display device, an exposure apparatus which projects a pattern formed on a mask onto a photosensitive substrate by exposure is employed. This exposure apparatus has a mask stage supporting a mask and a substrate stage supporting a substrate, and projects a pattern of a mask to a substrate via a projection optical system while successively moving the mask stage and the substrate stage. In micro device producing, for higher integration of the device, it has been demanded to increase the fineness of the pattern to be formed on the substrate. To meet this demand, higher resolution of the exposure apparatus has been desired. As one of the means for realizing this higher resolution, a liquid immersion exposure apparatus is proposed which fills a liquid in an optical-path space between a projection optical system and a substrate and performs an exposure process through the liquid, as disclosed in the following patent document 1.
Patent document 1: Pamphlet of International Publication Pamphlet No. 99/49504